You didn't say what the intended purpose was of the gun.
The powers that you mentioned I'm guessing you are shopping for a varmint rifle,the 4.5x14 would be an excellent choice.
If you are shopping for a big game rifle you may consider something like the 3.5x10 or the 2.5x8.
Usually the higher power scopes for varmint hunting have finer crosshairs. These are great during the day but are hard to see in low light situations.
The lower power scopes have crosshairs that are a little thicker and easier to see in low light.
The Leupold scopes are hard to beat for the money.